Rosa Callahan, a welfare mother living in a middle-income area of Montgomery County, would like to live the way her neighbors do.

But she can't. So instead, she pretends.

The eight-member Callahan family lives in a neat, four-room brick house in Wheaton. The house, with its ample yard, is away from the main roads, surrounded by the relative quiet of suburbia. Like the rest of the neighborhood, it projects an image of modest good fortune.

Inside it is different. The rugs in the home were scavenged from somebody else's trash pile. So were the mattresses and box springs some of her children sleep on. Some of the lamps were crafted out of tin cans.

"You do what other people do," Callahan said during a recent interview. "But inside, your house is different, and your neighbors don't know."

To keep up the charade, Callahan -- not her real name -- and others like her travel miles from home to shop in supermarkets in less affluent areas where no one they know would see them using food stamps to pay the bill -- and where cashiers don't greet food stamps with poorly disguised contempt. And they discourage their children from bringing friends home to play.

For Rosa Callahan and her family are part of a dwindling minority in Montgomery County, one of the two wealthiest counties in the nation. They are poor.

Living in a county whose median family income approaches $29,000, the eight Callahans make do on the $10,300 annual salary that Callahan earns from her federally funded job, plus $176 monthly in food stamps and general assistance payments.

The rent on their home is $350 a month, and the utilities cost another $150 to $200 each month. Four weeks' worth of food costs about $300. "After you eat and pay the rent, there isn't much left," Callahan said.

Under extreme pressure just to make ends meet, the Callahans also feel the additional pressure of isolation. According to the figures kept by Montgomery County's Department of Social Services, there are fewer and fewer families like them.

During the last two years the number of welfare clients in Montgomery County dropped from 5,250 to 4,000, and the decline is expected to continue.

'I'm sorry to see the decline (in the caseload), County Executive Charles W. Gilchrist said recently. "It means the people who need help can't afford to live here."

"It's not like West Virginia, where I'm from, where you're all broke together," said Rita Jones, a close friend of Rosa Callahan's who lives in South Rockville and also receives public assistance.

"At Christmas," added the friend, whose name has also been changed, "you hope to God the neighborhood kids don't come in, because your kids don't get anything but shoes."

"We don't have a box for a table," Callahan said recently, "but the way we live in this county, we are poor."

One of her sons wears $30 sneakers, and several other children ride their own bicycles -- all donated. Her teen-aged daughter goes to the movies with friends only if someone else is buying the tickets, and another son had to go to work to earn the $57 he needed to buy his high school graduation pictures.

"If someone comes to pick up my kids, I don't want [the children] to feel like they can't ask them in, but on occasion I have said, 'Please go out and talk.' That's wrong; this is their home. But you wonder what their friends' houses are like, if you sink down in the rugs...,"

The Callahans' rented brick house is brightly decorated in reds and golds, and equipped with teen-age "necessities," a record player and a television set.

Some of the rest of the furnishings are the fruits of what Callahan calls scavenger hunts. "I get in a car with a girlfriend and made it fun," she said. We'd drive past apartments in Rockville before the trash man came...

"If I thought much about it, I'd be upset," she added. "But it's something I have to live with."

At another point in a recent coversation, Callahan laughed. "I try to be resourceful," she said, "but sometimes my mind just goes blank... I feel like a facade in some ways because I project one thing and feel another. In the back of my mind, at work, I'm always worrying..."

The Callahans, who are black, moved to Montgomery County five years ago from Southeast Washington. Their home there had been bought up by housing renovators. "I must have called 100 real estate places in D.C., but all they had to show me were houses with the floors falling out," said Callahan.

"Montgomery has good schools; it offers a lot for the children," she added. "It's clean and it's not like being jumbled together... I didn't know it was so affluent, I really didn't."

In Montgomery County's Department of Social Services there is growing concern that, as Montgomery County grows more and more affluent, there will be fewer and fewer places for people like the Callahans.

Rents for apartments in Montgomery are higher than rents anywhere else in the area. "If you look at the rents here," said Clarence Lester, the associate director of administration in the social services department, "the average welfare recipient couldn't afford to pay them."

It is not much easier for welfare recipients to get by in other metropolitan area jurisdictions, either. Like Montgomery, the District of Columbia also has experienced a steady decline in its welfare rolls, going from 31,000 welfare clients two years ago to about 30,600 today.

Some District officials attribute the decline to the same forces that are driving welfare families out of areas such as Montgomery and Alexandria, which has also experienced a steady decline in welfare cases. The factors they cite are: the high cost of living, particularly the soaring cost of housing.

But if families are moving out of Washington's increasingly affluent areas, no one seems sure where they are going.

Some jurisdictions, such as Prince George's County, have experienced an increase in welfare clients over the past year. There are now more than 7,100 families in the largest federal welfare program administered by Prince George's, an 11 percent increase over a year ago.

Other areas, including Fairfax County, have seen their welfare case loads rise slightly -- but not as much as their population. Fairfax, like Montgomery one of the wealthiest counties in the nation, had about 2,400 families on welfare last month.

And not everyone agrees with the premise that a decrease in the welfare rolls means an exodus of the poor. Albert Russo, the director of D.C. Department of Human Resources, asserted that, in Washington, more welfare mothers are finding work and thus leaving the welfare rolls.

The Callahans' situation, however, was the exact opposite of what Russo describes. About the time they moved to Montgomery, Callahan's husband, a construction worker, was disabled by a back injury.

After two years his disability checks stopped. The next year, their savings ran out. "My landlady suggested we apply for welfare. All I thought about that was 'ugh,'" she said.

So Rosa Callahan went back to work. But she found she had to apply for public assistance just to get by. Now the rhythm of family life depends, to some extent, on the arrival of welfare payments and food stamps.

Callahan's children come home from school with requests she can't fill right away and sometimes never -- $17 for dance shoes for a musical or $58 for a class outing.

Not long ago Rosa Callahan wanted to take her children to an amusement park in southern Maryland. She figured it would cost about $60 for the trip. "If I could have scrounged up the $60, it wouldn't have been too much for some peace of mind, but I couldn't do it."